The invention relates to a double-track multiple-axle motor vehicle including at least two fuel tanks, in which a fuel for generating drive energy for a vehicle drive unit can be stored at a high pressure in the order of magnitude of 300 bar and more. Each tank includes a safety valve device having a temperature-sensitive element which monitors only a partial region of the tank surface. The safety valve device allows at least a partial quantity of the stored fuel to escape from the respective tank at a relatively high temperature, which can occur, for example, in the case of a fire. With respect to the prior art, reference is made by way of example to DE 11 2008 003 549 T5.
High pressure tanks for vehicles, in which, for example, hydrogen (as an energy source for an energy converter for generating drive energy) is stored, have to be depressurized in the case of a vehicle fire, in order to not allow a safety-critical situation to arise. For this purpose, at least a partial quantity of the stored hydrogen is possibly blown off in a timely and targeted manner into the surroundings. Here, there is also a vehicle fire when merely, for example, a tire of a vehicle wheel is burning, which might be brought about, for example, maliciously by a person. The fastest possible reaction to an emergency situation of this type is therefore called for, but cannot take place with absolute certainty when the tanks with their safety valve devices with temperature-sensitive elements which are often integrated into said safety valve devices are arranged in such a way as is disclosed in the document cited at the outset.
It is an object of the present invention to provide a corrective measure for said problem.
This and other objects are achieved by a motor vehicle in accordance with embodiments of the present invention. The temperature-sensitive elements of at least two tanks are arranged such that the spacing between a left-side wheel of the vehicle axle, in the vicinity of which the at least two fuel tanks are arranged in the vehicle, and the temperature-sensitive element which lies closest to the left-side wheel does not differ significantly from the spacing of the other one of said two temperature-sensitive elements from the right-side wheel of the vehicle axle. Here, a linearly measured spacing in the order of magnitude of 25% of the width of the vehicle is considered to be an insignificant spacing difference.
First, the term of a temperature-sensitive element is discussed. This can be an element which in some suitable way measures the temperature which prevails locally, that is to say in the immediate vicinity of the temperature-sensitive element, and forwards the measurement result, for example to an electronic or else mechanical control unit which, in the case of an impermissibly high temperature, triggers opening of the safety valve device or of a safety valve which is provided in the latter. As a result, a partial quantity of fuel (for example, hydrogen) can then escape from the tank. However, the temperature-sensitive element can also be an element which fulfills the two functions, melts or bursts, for example if an impermissibly high temperature prevails, and as a result exposes an outflow opening which is provided in the tank and was previously closed by way of said element.
Now discussing the features and measures which are proposed to this extent, it is therefore ensured that a temperature-sensitive element is situated in each case relatively close by both in the case of a fire (or blaze) at a left-side vehicle tire and at a right-side vehicle tire. As a result (with reference once again for the sake of simpler presentation to DE 11 2008 003 549 T5 and FIG. 1(C) therein), in the case of a fire at the right-side tire, said fire does not have to pass beyond all the tanks to the temperature-sensitive elements which are provided only on the left side first, before said elements can react. Rather, by way of the arrangement of the temperature-sensitive elements which is proposed in the present case, a reaction can occur almost instantaneously in the case of a one-sided fire. If, in an analogous manner to said prior art which has already been cited multiple times, the fuel tanks are at least approximately cylindrically shaped and are installed in the vehicle so as to lie with their cylinder axis in the vehicle transverse direction, in the case of two tanks the temperature-sensitive element in one of the two tanks is arranged so as to lie on the left, that is to say on the left head region or base region of the tank, and the temperature-sensitive element of the other tank is arranged so as to lie on the right in the vehicle, that is to say on the right head region or base region of the tank.
In the case which is mentioned above and in which more than two fuel tanks can also be provided, it can be provided, furthermore, that the filling and removal valve apparatuses of the tank lie on the same side of the vehicle in relation to the floor area of the vehicle. The laying of the lines to the filling and removal valve apparatuses of the plurality of tanks is simplified considerably as a result. In contrast, even in the case where, at any rate in one of the tanks, the temperature-sensitive element is integrated into the safety valve device and the latter for its part is integrated into the filling and removal valve device, the complexity is still acceptably low. This is by virtue of the fact that, in at least one of the other tanks, at least the temperature-sensitive element is now laid at its other end which lies opposite the filling and removal valve apparatus. For example, a safety valve apparatus which is also commonly known under the abbreviation “TPRD” with an integrated temperature-sensitive element can also be integrated into what is known as the “blind boss”, which is a closure plug for a partial aperture, necessitated by manufacturing technology, in the base region of currently developed high pressure tanks for motor vehicles, which partial aperture has to be closed in any case and can now be closed by way of a “TPRD” with a blind plug function. A simple filling and removal valve apparatus without an integrated “TPRD” can then be situated on said tank so as to lie opposite on the top side.
Within the context of one advantageous development, the safety valve devices including their temperature-sensitive elements of all the fuel tanks which are installed in the vehicle can be designed such that temperature-induced opening of the safety valve device of one of the tanks also makes an outflow of fuel which is situated in the tank possible at the safety valve device/devices of the other tank or at least one other tank. In this way, critical quantities of fuel or hydrogen can be discharged as rapidly as possible from the complete tank system of the vehicle. One contemplated embodiment for this purpose is that the safety valve devices of the fuel tanks are arranged such that a blow-off opening of a first safety valve device, the temperature-sensitive element of which lies close to a first (for example, the left) vehicle side, is oriented toward the temperature-sensitive element of a second safety valve device, which temperature-sensitive element lies close to a second (for example, the right) vehicle side. Therefore, if hydrogen flows out from a safety valve device of a first tank, which safety valve device lies, for example, on the left side in the vehicle, because a fire has broken out close to said location, said hydrogen is ignited and the flame which results is directed directly toward the safety valve device which lies on the right in the vehicle or toward its temperature-sensitive element on account of the proposed orientation of the blow-out opening. As a result, said second safety valve device also opens as soon as possible. Another or an additional possibility for quasi-mutual opening of safety valve devices which in practice lie opposite one another in the vehicle (or temperature-sensitive elements of the safety valve devices) consists in that the safety valve devices of at least two tanks are connected to one another via a pressure line which is connected to that side of the safety valve devices which faces the storage volume of the respective tank. Via said pressure line, the storage volumes of at least two tanks are in practice connected directly to one another, with the result that, upon opening of a single safety valve device, the tank contents of all tanks which are connected to one another can flow out through said safety valve device. By way of a design of this type, only a single common filling and valve device apparatus can also be provided for the fuel tanks which are connected to one another via said pressure line, in order to simplify the construction.
Returning to the problem that one of the vehicle tires catches fire, it is proposed, furthermore, that those regions of the vehicle body which delimit a space which surrounds the wheels of a vehicle axle which is close to the tank are of flame retardant configuration. Here, corresponding trim elements in the wheel arches of the vehicle body are meant, in particular, which trim elements can prevent as far as possible a fire which starts there or a fire which is lit there from spreading to the outer sides of the fuel tanks of the vehicle.
Exemplary embodiments which will be described in the following text are shown in the appended outline sketches in a manner which is greatly simplified to the essentials.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.